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Influence of Tip End-plate on Noise of Small Axial Fan

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Journal of Thermal Science 2017年第1期26卷 30-37页

作者： MAO Hongya WANG Yanping LIN Peifeng JIN Yingzi Toshiaki Setoguchi heuy dong kim Key Laboratory of Fluid Transmission Technology of Zhejiang Province Zhejiang Sci-Tech University Department of Mechanical Engineering Saga University School of Mechanical Engineering Andong National University

In this work, tip end-plate is used to improve the noise performance of small axial fans. Both numerical simulations and experimental methods were adopted to study the fluid flow and noise level of axial fans. Four modified models and the prototype are simulated. Influences of tip end-plate on static characteristics, internal flow field and noise of small axial fans are analyzed. The results show that on basis of the prototype, the model with the tip end-plate of 2 mm width and changed length achieved best noise performance. The overall sound pressure level of the model with the tip end-plate of 2 mm width and changed length is 2.4 dB less than that of the prototype at the monitoring point in specified far field. It is found that the mechanism of noise reduction is due to the decrease of vorticity variation on the surface of blades caused by the tip end-plate. Compared with the prototype, the static pressure of the model with the tip end-plate of 2 mm width and changed length at design flow rate decreases by 2 Pa and the efficiency decreases by 0.8%. It is concluded that the method of adding tip end-plate to impeller blades has a positive influence on reducing noise, but it may diminish the static characteristics of small axial fan to some extent. © 2017, Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg.

关键词： Axial flow Fans Flow of fluids Noise abatement Numerical methods

A Study of the Gas Flow through Air Jet Loom

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Journal of Thermal Science 2007年第2期16卷 159-163页

作者： heuy-dong kim Chae-Min Lim Ho-Joon Lee Doo-Hwan Chun School of Mechanical Engineering Andong National University388Songcheon-dongAndong 760-749KoreaE-mail:kimhd Korea Textile Machinery Research Institute 300Sampoong-dongKyeongsan 712-210Korea

Air jet loom, as one of the shuttleless looms, transports a yam into warps using viscosity and kinetic energy of an air jet. Performance of this picking system depends on the ability of instantaneous inhalation/exhaust, configuration of nozzle, operation characteristics of a check valve, etc. In the recent past, many studies have been reported on the air jet discharged from a nozzle exit, but studies for understanding the flow field characteristics associated with shear layer and shock wave/boundary layer interaction in the nozzle were not conducted enough. In this paper, a computational study was performed to explain the flow field in the air jet nozzle with an acceleration tube and validated with previous experimental data available. The results obtained from the computational study show that, in the supersonic flow regime, the flow field depends significantly on the length of acceleration tube. As nozzle pressure ratio increases, drag force acting on the string also increases. For a longer acceleration tube, the total pressure loss is large, owing to the frictional loss.

关键词： compressible flow nozzle shear layer shock wave air jet loom shuttleless loom

Effect of Inlet Guide Vanes on the Performance of Small Axial Flow Fan

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Journal of Thermal Science 2017年第6期26卷 504-513页

作者： LIU Yang LIN Zhe LIN Peifeng JIN Yingzi Toshiaki Setoguchi heuy dong kim Key Laboratory of Fluid Transmission Technology of Zhejiang Province Zhejiang Sci-Tech University Department of Mechanical Engineering Saga University School of Mechanical Engineering Andong National University

Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle are designed, which are mounted on the casing and located at the upstream of the impeller of the prototype fan. Both steady and unsteady flow simulations arc performed. The steady flow is simulated by the calculations of Navier-Stokes equa- tions coupled with RNG k-epsilon turbulence model, while the unsteady flow is computed with large eddy simu- lation. According to the theoretical analysis, the inlet guide vanes with outlet angle of 60° are regarded as the op- timal inlet guide vanes. The static characteristic experiment is carried out in a standard test rig and the aerody- namic noise is tested in a semi-anechoic room. Then, performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan. The results show that there is reasonable agreement between the simu- lation results and the experimental data. It is found that the static characteristics of small axial flow fan is im- proved obviously after installing the optimal inlet guide vanes. Meanwhile, the optimal inlet guide vanes have effect on reducing noise at the near field, but have little effect on the noise at the far field.

关键词： small axial flow fan inlet guide vanes static characteristics aerodynamic noise internal flow characteristics

Control of the Asymmetric Flow in Rocket Nozzles

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Journal of Thermal Science 2013年第2期22卷 97-102页

作者： Shigeru Matsuo Shotaro Suetsugu Junji Nagao Tokitada Hashimoto Toshiaki Setoguchi heuy dong kim Department of Advanced Technology Fusion Saga University Graduate School of Science & Engineering Saga University Institute of Ocean Energy Saga University School of Mechanical Engineering Andong National University

In some rocket nozzle flows, the existence of the transition from FSS to RSS and the occurrence of asymmetric flow are known in previous researches. As a result, the transition causes excessive side-loads that may damage the nozzle. Thus, it is important to investigate the method in order to control the asymmetric flow separation. In the present study, the relationship between the asymmetric separation and the rate of change of the pressure ratio with time was investigated from the point of view of the transition from FSS to RSS in the supersonic nozzle experimentally. Further, change of the flow separation by using step and cavity, and the possibility of the control was demonstrated. As a result, it was shown that the method using a cavity was effective for the control of the separation pattern.

关键词： Compressible flow Asymmetric shock wave Rocket nozzle Control Experiment

Effect of the Uneven Circumferential Blade Space on the Performance of Small Axial Flow Fan

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Journal of Thermal Science 2016年第6期25卷 492-500页

作者： LIU Yang LIN Zhe LIN Peifeng JIN Yingzi Toshiaki Setoguchi heuy dong kim Key Laboratory of Fluid Transmission Technology of Zhcjiang Province Zhejiang Sci-Tech UniversityHangzhou310018China Department of Mechanical Engineering Saga UniversityHonjo-machiSaga840-8502Japan School of Mechanical Engineering Andong National UniversitySeongcheon-Dong1375Gyeongdong-RDAndongGyeongsangnuk-DO760-749Korea

Effects of the uneven circumferential blade space on static characteristics and aerodynamic noise of a small axial flow fan are studied in this *** blade angle modulation is adopted to design a series of unequally spaced fans,which have different maximum of modulation angular *** steady flow is simulated by the calculations of Navier-Stokes equations coupled with RNG k-epsilon turbulence model,while the unsteady flow is computed with large eddy *** to theoretical analysis,a fan with a maximum of modulation angular displacement of 6° is regarded as the optimal unequally spaced *** experiment of static characteristic is carried out in a standard wind tunnel and the aerodynamic noise of both fans is tested in a semi-anechoic ***,performances of the optimal unequally spaced fan are compared with those of the prototype *** results show that there is reasonable agreement between the simulation results and the experimental *** is found that the discrete noise of the optimal unequally spaced fan is lower than that of the prototype fan at the near field monitoring *** can be explained that the total pressure fluctuation of the optimal unequally spaced fan is much more regular than that of the prototype fan.

关键词： prototype blade fluctuation uneven turbulence aerodynamic rotating unsteady Mellin slowly

Effect of Axisymmetric Sonic Nozzle Geometry on Characteristics of Supersonic Air Jet

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Journal of Thermal Science 2004年第2期13卷 121-126页

作者： Shigeru MATSUO Masanori TANAKA Yumiko OTOBE Hideo KASHIMURA heuy-dong kim Toshiaki SETOGUCHI Department of Mechanical Engineering Saga University 1 Honjo-machi Saga-shi Saga 840-8502 Japan Department of Control and Information Systems Engineering Kitakyushu National College of Technology 5-20-1 Shii Kokuraminami-ku Kitakyushu-shi Fukuoka 802-0985 Japan School of Mechanical Engineering College of Natural Science Andong National University 388 Song-Cheon Dong Andong Kyung-Pook Korea

The effect of nozzle geometry on sonic line and characteristics of supersonic air jet was studied. Computational fluid dynamics was applied in this study. The axisymmetric nozzle geometries investigated were two different contour converging nozzles, two different conically converging sharp-edged nozzles and a sharp-edged orifice. The results show that the supersonic jet structure, sonic line and streamlines in supersonic jet are strongly influenced by the nozzle geometry, and the total pressure loss increases with the increase of Mach disk diameter. The present numerical simulation is an effective tool to evaluate compressible flows in supersonic air jet.

关键词： compressible flow supersonic jet non-equilibrium condensation simulation.

A Study of Under-expanded Moist Air Jet Impinging on a Flat Plate

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Journal of Thermal Science 2005年第4期14卷 334-340页

作者： Yumiko OTOBE Shigeru MATSUO Masanori TANAKA Hideo KASHIMURA heuy-dong kim Toshiaki SETOGUCHI Department of Control and Information Systems Engineering Kitakyushu National College of Technology5-20-1ShiiKokuraminami-kuKitakyushu-shiFukuoka 802-0985Japan Department of Mechanical Engineering Saga University1Honjo-machiSaga-shiSaga 840-8502Japan School of Mechanical Engineering College of Natural ScienceAndong National University388Song Cheon DongAndongKyung PookKorea

When a gas expands through a convergent nozzle in which the ratio of the ambient to the stagnation pressures is higher than that of the critical one, the issuing jet from the nozzle is under-expanded. If a flat plate is placed normal to the jet at a certain distance from the nozzle, a detached shock wave is formed at a region between the nozzle exit and the plate. In general, supersonic moist air jet technologies with non-equilibrium condensation are very often applied to industrial manufacturing processes. In spite of the importance in major characteristics of the supersonic moist air jets impinging to a solid body, its qualitative characteristics are not known satisfactorily. In the present study, the effect of the non-equilibrium condensation on the under-expanded air jet impinging on a vertical flat plate is investigated numerically in the case with non-equilibrium condensation, frequency of oscillation for the flow field becomes larger than that without the non-equilibrium condensation, and amplitudes of static pressure become small compared with those of dry air. Furthermore, the numerical results are compared with experimental ones.

关键词： compressible flow non-equilibrium condensation impinging jet simulation.

Investigation on Temperature Separation and Flow Behaviour in Vortex Chamber

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Journal of Thermal Science 2015年第2期24卷 149-154页

作者： Yuhi Matsuno Yusuke Fukushima Shigeru Matsuo Tokitada Hashimoto Toshiaki Setoguchi heuy dong kim Graduate School of Science and Engineering Saga University Department of Advanced Technology Fusion Saga University Institute of Ocean Energy Saga University School of Mechanical Engineering Andong National University

In the previous researches, it is known that the swirl flow in circular pipe causes the temperature separation. Recently, it is shown that the temperature separation occurs in a vortex chamber when compressed air are pumped into this device from the periphery. Especially, in a cavity installed in the periphery of the chamber, the highest temperature was observed. Therefore, it is expected that this device can be used as a heat source in the engineering field. In recent researches, the mechanism of temperature separation in vortex chamber has been investigated by some researchers. However, there are few researches for the effect of diameter and volume of vortex chamber, height of central rod and position of cavity on the temperature separation. Further, no detailed physical explanation has been made for the temperature separation phenomena in the vortex chamber. In the present study, the effects of chamber configuration and position of the cavity on temperature separation in the vortex chamber were investigated experimentally.

关键词： Compressible flow Vortex chamber Cavity flow Temperature separation

Effects of Perforation Number of Blade on Aerodynamic Performance of Dual-rotor Small Axial Flow Fans

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Journal of Thermal Science 2015年第2期24卷 123-130页

作者： HU Yongjun WANG Yanping LI Guoqi JIN Yingzi Toshiaki Setoguchi heuy dong kim The Zhejiang Provincial Key Laboratory of Fluid Transmission Technology Zhejiang Sci-Tech University Department of Mechanical Engineering Saga UniversityHonjo-machiSaga840-8502Japan School of Mechanical Engineering Andong National UniversitySeongcheon-Dong1375Gyeongdong-RDAndongGyeongsangnuk-DO760-749Korea

Compared with single rotor small axial flow fans, dual-rotor small axial flow fans is better regarding the static characteristics. But the aerodynamic noise of dual-rotor small axial flow fans is worse than that of single rotor small axial flow fans. In order to improve aerodynamic noise of dual-rotor small axial flow fans, the pre-stage blades with different perforation numbers are designed in this research. The RANS equations and the standard k-e turbulence model as well as the FW-H noise model are used to simulate the flow field within the fan. Then, the aerodynamic performance of the fans with different perforation number is compared and analyzed. The results show that：（1） Compared to the prototype fan, the noise of fans with perforation blades is reduced. Additionally, the noise of the fans decreases with the increase of the number of perforations. （2） The vorticity value in the trailing edge of the pre-stage blades of perforated fans is reduced. It is found that the vorticity value in the trailing edge of the pre-stage blades decreases with the increase of the number of perforations. （3） Compared to the prototype fan, the total pressure rising and efficiency of the fans with perforation blades drop slightly.

关键词： dual-rotor small axial flow fans the blade with perforation perforation number aerodynamic per-formance